Fennel: Uses, Side Effects, and More (2023)

Fennel is an annual herb in the parsley family. its scientific name isanise(P. Anis). Fennel is native to Egypt and the eastern Mediterranean. However, it also grows in other parts of the world such as Europe, Asia, Africa and the Americas.

Fennel contains the following compounds that may be responsible for its effects:

  • Acetophenone
  • lost
  • Anisitol
  • destroy
  • Limonene
  • p-anisaldehyde
  • pen

This article explains what you should know about fennel - its possible uses, side effects and interactions.

In the United States, dietary supplements are not regulated like drugs, which means that the Food and Drug Administration (FDA) does not approve products for their safety and effectiveness before they are released on the market. When possible, choose dietary supplements that have been tested by a trusted third party, such as BUS. Pharmacopoeia (USP), ConsumerLab.com, or NSF International.

However, even when supplements have been third-party tested, they are not necessarily safe or universally effective for everyone. Therefore, it's important to discuss any supplements you're considering taking with your doctor, and ask about possible interactions with other supplements or medications.

supplementary facts

  • Active ingredients): Acetophenone, Anethole, Aniseol, Estratol, Limonene, p-anisaldehyde, Pinnen
  • alias(n): Anis,anise,P. Anis, fennel (fruitP. Anis)
  • Legal Status: Over-the-counter drug in the United States; substance added to food
  • recommended dose: May vary depending on dosage form and medical condition
  • security: For use in children, pregnant and nursing parents, but more information is needed to better assess safety

uses of fennel

Dietary supplement use should be individualized and reviewed by a healthcare professional such as a registered dietitian, pharmacist, or healthcare provider. No dietary supplement is intended to treat, cure or prevent any disease.

As with many natural products, more extensive research is needed. But people may use fennel for various reasons.


The results of the 2022 review show that people withtype 2 diabetes(high blood sugar caused by a problem with the way the body regulates sugar and uses it for energy) can be taken in 5 grams (g) of powdered fennel daily for 60 days.

The possible effects areLowers fasting blood sugar levels (before meals).and reducetotal cholesterolandTriglyceride Spiegel.

Because this study was a small study, its findings need to be supported by broader, larger studies evaluating the health effects of aniseed.diabetes.


Findings of one review suggest that people with functional dyspepsia may benefit from taking 3 grams of fennel powder 3 times daily with meals for 4 weeks.Featureindigestionis a disorder in which dyspepsia symptoms (pain or discomfort in the upper abdomen) begin for at least 12 weeks within the past 6 months.

Although the results look promising, more research with more participants is needed to better understand how aniseed works.

irritable bowel syndrome

Research shows that people withirritable bowel syndrome(IBS) can benefit from fennel oil. In these clinical studies, a group of study participants took anise oil as enteric-coated (EC) capsules, called AnisEncap.

Take 600 milligrams (mg) (three 200 mg capsules) daily for four weeks before meals.

The group taking AnisEncap reported fewer of the following symptoms compared to the group taking AnisEncapplacebo(intentional administration of drugs that did not work in the control group):

  • Sura reflux
  • diarrhea
  • gas(gas)
  • stomachache

Symptoms also eased in the AnisEncap groupdepressedand seriousconstipate.

In addition, this group reported a higher quality of life.

Although the results are encouraging, higher quality and larger clinical trials are needed to better assess the effects of star anise and better understand how it works.

Natural Remedies for Irritable Bowel Syndrome


Results of a small six-week study showed that people withMigraineApplying anise oil cream to the forehead and temple area (behind the ears) may help.

The group of study participants who used anise oil cream had fewer migraine attacks than the group that did not use the cream. When there is an attack, it doesn't last that long. However, the cream did not seem to affect the severity of migraine attacks.

While this research is promising, more research and larger clinical trials are needed.

nasal allergies

Fennel was compared with fluticasone nasal spray for use in the nose (nasal) in one small clinical study.allergy.

Participants in the anise group received nasal drops containing 200 micrograms (mcg) of an anise almond oil aqueous extract into each nostril every 12 hours for four weeks.

Findings from this study suggest that anise may relieve nasal allergy symptoms better than fluticasone nasal spray, which includes the Flonase and Flovent brands.

Larger clinical trials and extensive research are still needed to assess these effects.

premenstrual syndrome

Alcohol extract from fennel powder may provide pain relief, results of a small studypremenstrual syndrome(PMS) symptoms better than placebo. In this clinical study, the dose was 330 mg per day.

Because many clinical studies have used fennel in combination with other plant materials, more research is needed to better evaluate the effects of fennel on its own.

Natural Remedies for Menstrual Cramps

hot flashes

Another small clinical study also investigated the possible use of an alcoholic extract of ground fennel to relieve certain symptomsmenopauseSymptoms such as hot flashes.

In the study, a group of participants took 990 mg of the extract daily for four weeks. The extract seems to reduce the severity and frequency of hot flashes.

However, no more extensive clinical research has been conducted comparing aniseed with typical hormone therapy and its effects on various hormone levels.

Natural Remedies for Menopause Symptoms

What are the side effects of fennel?

Like many medications and natural products, fennel can have side effects.

frequent side effects

There is little information about common side effects of fennel. However, the FDA has added fennel to its list of substances added to foods.

serious side effects

Typical levels of fennel in foods are generally considered safe.In one study, no serious side effects were reported with enteric-coated (EC) fennel oil capsules (AnisEncap).

However, severe allergic reactions are serious side effects that can occur with any medicine, including herbal medicines. if you havesevere allergic reactionStar anise can cause symptoms such as difficulty breathing, itching and rashes.

If you have a severe allergic reaction or any symptoms that seem life-threatening, call 911 and get medical help right away.


Your doctor may advise you not to use fennel if any of the following conditions apply to you:

severe allergic reaction: You should not take this medicine if you have or have ever had a severe allergic reaction to anise or any of its constituents (ingredients or parts).

Pregnant: Fennel has historically been considered safe and is traditionally used in mealsPregnant.However, components (components or parts) of essential oils may pass into the unborn fetus and cause harmful effects.Anise oil and anise alcohol extracts should be avoided. Aqueous (water-based) extracts of anise are preferred during pregnancy.Contact your doctor to discuss the benefits and risks before using fennel during pregnancy.

breast-feeding: As during pregnancy, aniseed use has historically been considered safe for nursing parents and a way to increase milk production. However, there are no reliable high-quality clinical studies to support this use or effect.Not much is known about the safety of aniseed for breastfed infants.Breast milk contains fennel, but at lower levels than in breastfeeding parents. A small study showed no side effects in breastfed babies.

However, there have been reports of breastfeeding parents drinking too many teas containing fennel and other herbs, which can be toxic to nursing babies. Fennel can also change the smell of breast milk. Some breastfeeding parents also experience abnormal liver values.

Consult your doctor to discuss the benefits and harms of anise, especially anise oil and alcoholic extracts of anise.Most anise product labels may not state this, although the possible exception is water-based anise extractbreast-feedingparents.

Kinder: A small clinical study shows that use of fennel by breastfeeding parents has no adverse effects on breastfed infants.However, these children are at risk of poisoning if nursing parents drink too much tea containing fennel and other herbs.

Also, many anise products may be aimed at adults rather than children.If you are considering giving fennel to your child, talk to your doctor.

Seniors over 65 years old: Elderly people participated in clinical trials of fennel, but these trials were small.Some older adults tend to be at higher risk of drug side effects. Therefore, use star anise with caution.

diabetes: Fennel can affect your blood sugar.Your doctor may want to monitor your blood sugar levels closely -- especially if you're taking diabetes medications.

breast cancer: Endocrine (hormone) therapy is often used after certain types of breast cancer surgery. This is to prevent these types of breast cancer from happening again.fennel can have someEstrogen- Have similar effects and may interfere with endocrine therapy, physicians should avoid.

Dosage: How Much Fennel Should I Take?

Always consult your doctor before taking any supplement to make sure the supplement and dosage are right for your individual needs.

Although there are some studies on fennel in humans, high-quality clinical trials are still needed.Therefore, there are no guidelines on the appropriate dosage for each situation.

When taking fennel, follow your doctor's advice or label directions.

What happens if I eat too much fennel?

At typical levels in foods, fennel is generally considered safe.

However, in case of overdose, possible symptoms of anise poisoning may include:

  • Abnormal hormone levels—may affect sperm count or fertility
  • breathing problems from an allergic reaction, orexcess fluid in the lungs
  • high blood sugar
  • nausea and vomiting
  • epileptic seizure
  • severe bleeding or clotting problems

Some fennel products may also be contaminated with false star anise, which can cause the following serious side effects:

  • diarrhea
  • hallucination
  • epileptic seizure
  • Vomit

If you suspect you are experiencing life-threatening side effects, seek immediate medical attention.


In general, there is limited information on potential drug-fennel interactions. However, most data are based on in vitro (cell culture) and in vivo (animal) studies.

Be careful when taking fennel and take the following precautions:

CYP2C9 Substrate Drugs: CYP2C9 is a liver protein normally responsible for the breakdown and excretion of certain drugs. Some examples of CYP2C9 substrates can be:blood pressurecalled drugsCozaar (losartan), known as blood thinnersJantoven (warfarin)and an antiattackA medicine called dilantine (phenytoin).

Fennel can cause the CYP2C9 protein to work faster and break down these drugs more quickly, making them less effective.Therefore, if you take fennel with any of these medications, your doctor may need to monitor you closely and make any necessary adjustments to your medications.

hypnotics: Various drugs can make you drowsy. Some examples include codeine for symptom reliefpainandstabilitycontribute to reliefanxietyormuscle cramps. Fennel can increase this side effect, making you excessively sleepy and drowsy.

Hormone therapy:Fennel has estrogen-like effects.Because of this, fennel may interact with endocrine (hormone) therapy for some types of breast cancer, menopausal hormone therapy, and hormonal birth control pills.

It's important to read a supplement's ingredient list and nutritional information carefully to understand what ingredients are present and how much each ingredient is. Please review this dietary supplement label with your healthcare practitioner to discuss possible interactions with food, other dietary supplements, and medications.

How to store star anise

Since storage instructions may vary for different natural products, read directions and the package label on the container carefully.

Lock up your medications out of the sight and reach of children and pets, preferably in a cupboard or closet. Store in a cool, dry place and discard after one year or as directed on package.

Avoid throwing unused and expired medicines down the drain or toilet. Visit the FDA's website to learn where and how to dispose of all unused and expired medications. You can also find litter boxes in your area.

Ask your pharmacist or healthcare provider questions about disposing of your medicines or supplements.

similar supplement

Fennel may help treat high blood sugar, irritable bowel syndrome (IBS), migraines, allergies,menstruationSymptoms and menopause.

Other potentially similar dietary supplements may include:

  • black cohosh: may useblack cohoshIt's menopause. However, according to the National Center for Complementary and Integrative Health (NCCIH), results on black cohosh's effectiveness have been mixed.
  • plague: NCCIH Ocean,plagueMay reduce the frequency of migraines.It can also relieve allergy symptoms.However, due to the high risk of hepatotoxicity, it is no longer recommended.
  • chaste tree: Preliminary studies suggest thatchaste treeMay help relieve menstrual symptoms. But the evidence is not enough to draw one conclusion or another.
  • chromium: Not enough evidencechromiumMay help lower blood sugar.
  • Probiotics: possible useProbioticsMay include irritable bowel syndrome and allergy relief. Although there is some evidence to support this, it is not a clear and definitive conclusion. Further high-quality research is still needed.
  • valerian: Several studies support valerian for relieving menopausal symptoms. However, more high-quality studies with solid evidence are needed to better assess the effects of valerian.
  • Vitamin B2 (riboflavin): There is some evidence -- but not overwhelming evidence -- that riboflavin might reduce the number of migraines you get.

frequently asked questions

  • What is the most common form of fennel?

    Fennel comes in a variety of dosage forms, liquid being probably the most common.

  • Are there any fennel products from US manufacturers?

    Yes. There are aniseed products available from US manufacturers.

  • Does Fennel Have Health Benefits?

    Yes. Aniseed is a source of B-complex vitamins, including thiamine (vitamin B1), riboflavin (vitamin B2), niacin (vitamin B3), and pyridoxine (vitamin B6). It is also a source of other vitamins, such as vitamins A and C. As for minerals, it is a source of calcium, copper, iron, magnesium, manganese, potassium and zinc.

  • Are star anise and star anise the same thing?

    No. star anise(anise) and star anise (that's right) have similar flavor profiles and uses. However, they are not from the same plant. Star anise is a herb in the parsley family, and star anise is the dried fruit of the star anise tree.

  • Is aniseed the same as licorice?

    No. Aniseed and licorice have very similar flavor profiles, but they do not come from the same plant. Fennel is in the parsley family and licorice is in the pea family.

  • Is fennel just another word for fennel?

    No. Fennel and fennel are both herbs in the same family of Umbelliferae. But fennel is in the parsley family and fennel is in the carrot family. They are not from the same plant.

  • How to take star anise safely?

    To safely take natural products like fennel, tell your doctor and pharmacist about any changes in your medications.These include over-the-counter (OTC), herbal, natural medicines, and dietary supplements.
    They can help prevent possible interactions and side effects. You can also make sure you test fennel in the correct dosage.

Sources and Precautions for Anise

Fennel comes from a variety of sources.

Food Sources of Star Anise

Fennel occurs naturally as a plant in the parsley family.Star anise (fennel fruit) can be used as a spice after it is ripe and dried.

The FDA has added fennel to the list of substances approved for addition to foods.

Anise and anise oil are used as a flavoring agent in a variety of foods such as curries, salami, baked goods and desserts.

Anise Supplements

Fennel comes in the following forms:

  • capsule
  • body fluid
  • nasal spray
  • grinder
  • skin products, such as face creams

Which product is right for you depends on your preferences and desired results. Each product may also have slightly different features. Follow your healthcare provider's advice or label directions.


Fennel is an herb in the parsley family. It may be used to treat high blood sugar, indigestion (upset stomach), irritable bowel syndrome (IBS), migraines, allergies, menstrual cramps, and menopause.

As with many medicines and natural products, side effects and drug interactions still exist. More higher-quality, longer-term, and larger-scale clinical trials are still needed to better evaluate the efficacy and safety of fennel.

Before taking fennel, talk to a registered dietitian, pharmacist, or healthcare provider to make a safe choice.

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